Looper drive for double chain stitch sewing machines



g- 1960 c. .1. M. BENINK ETAL 2,950 695 LOOPEER DRIVE FOR DOUBLE CHAINSTITCH SEWING MACHINES Filed Nov. 1, 1957 v 4 Sheets-Sheet 2 INVENTORSChfishaan 30805 Marinas BEN/Mk Waller IRMSCHER WING MACHINES Aug. 30,1960 C. J. M. BENlNK ETAL LOOPER DRIVE FOR DOUBLE CHAIN STITCH SE FiledNOV. 1, 1957 4 Sheets-Sheet 5 [WV E N Tom; Chrisiv'aan Mar/nus 35 w mpIEMSL'HER A gE/Vf.

Fliwwiii Aug- 1 c. J. M. BENINK ETAL 2,950,695

LOOPEIR DRIVE FOR nousu-z CHAIN STITCH SEWING MACHINES Filed Nov. 1,1957 4 Sheets-Sheet 4 Fig. 7

Patented Aug. 30, 1960 LOOPER DRIVE FOR DOUBLE CHAIN STITCH SEWINGMACHINES Christiaan Joseph Marinus Benink and Walter Irmscher, both ofKaiserslautern, Pfalz, Germany, assignors to G. M. Pfatf A.G.,Kaiserslautern, Pfalz, Germany Filed Nov. 1, 1957, Ser. No. 693,994Claims priority, application Germany Nov; 2, 1956 4 Claims. (Cl.112-200) The invention relates to the drive means for the looper ofdouble chain stitch sewing machines of the type equipped with needle andbase feeding means generally referred to as compound feed.

/ Double chain stitch sewing machines which sew in downward direction ofthe arm as well as double stitch fiat sewing machines with needlefeeding means are already known in which the looper moves in'thedirection of sewing. In machines of this type the loop gripping anddiscarding motion of the looper is constant. When the stitch length ischanged, the conditions of stitch formation change likewise. Withloopers which operate in the direction of sewing it is also necessary toassist the looper during stitch formation by means of a thread spreadingdevice.

For the sake of dispensing with the usually complicated spreading deviceit has already been proposed for a double chain stitch fiat sewingmachine to make the looper operate perpendicularly to the direction ofsewing and to relate the needle evading movement cf the looper whichoccurs in the direction of sewing to the feeding operation. Thus, insewing machines of this type the needle evading movement is also changedproportionately as the stitch length is changed.

However, this is not satisfactory. Thus, for example, if the needleevading movement is arranged for a medium stitch length, then thismovement also becomes very small or very large when a very small orlarge stitch length is set up. Adjusting to stitch length zero resultsin no stitch formation at all because the looper no longer executes aneedle evading movement. Therefore, in order to adapt the needle evadingmovement to the different stitch lengths several adjusting possibilitiesare provided in the known machines.

It is an object of the present invention to eliminate the disadvantagesof the known types of machines which operate in accordance withdifferent basic principles by using'the simplest possible means.

In accordance with the invention the movement of the loopers in thedirection of sewing is composed of a constant movement and a variablemovement superimposed thereon which depends on the advancing movement ofthe needles. Thus in machines having loopers operating in the directionof sewing the loop catching and discarding movements and in machineshaving loopers op erating perpendicularly to the direction of sewing theneedle evading movement is composed of a constant and a variablemovement.

In machines where the transfer of the movement to the loopers or to thematerial feeding means takes place from the shaft of the drive mechanismby way of traction rods and rocker cranks this can be materialized inparticularly simple fashion in that the rocking crank for the constantlooper movement in the direction of sewing is journalled in arms of therocking crank for the advancing movement of the material.

Further objects of the invention and details as to the advantagesobtained thereby will become apparent flom the following description ofthe embodiment of the new looper drive illustrated in the accompanyingdrawings wherein:

Fig. 1 is a perspective view of a double chain stitch sewing machineadapted for feeding in arm downward direction with catcher operatingperpendicularly to the direction of sewing, provided with the catchdrive in accordance with the invention;

Fig. 2 is a front view of the machine, partly in section;

Fig. 3 is a section taken along line III-III in Fig. 2;

Fig. 4 is a plan view of the carrier arm with the cover plate removed;

Fig. 5 is a top view of the bridge and of the adjustable cams;

Fig. 6 is a sectional view of one of the cam members and its adjustingmember taken substantially along line VI-Vl in Fig. 5 with the camrotated through a 90 angle, and

Fig. 7 is a sectional view taken along line VIIVII in Fig. 6.

The standard 1 of the machine housing has an overhanging arm 2 intowhich merges a forwardly extending head 3 at one end while a downwardlyextending arm 4 is joined to the other end. The lower end of arm 4merges into a horizontal carrier arm 5, the free end of which ends upbelow head 3.

The main drive shaft 6 is journalled in arm 2 which carries the drivepulley 7 at the front end. The spring biased presser foot bar 8 with thepresser foot 9 and the reciprocating needle bar 10 which oscillates inthe direction of the carrier arm 5 and which carries two needles 11 isprovided in the head 3 in the usual manner.

The operation of the needle bar 10 is effected in a known manner fromthe drive shaft 6 by way of a crank for the reciprocating movement andan adjustable cam 12 for the to-and-fro oscillations. The cam 12 isprovided with a setting member 13 having a stopping groove 14 adapted tobe engaged by a detent 16 secured to one end of a yoke 15. Theadjustable cam 12 is operatively connected by way of a cam arm 17, adouble armed oscillator lever 18 and a draw bar 19 to the needle baroscillator.

The material feed dog 20 is mounted at the forward end of the carrierarm 5 being secured to the material feed bar 22 by means of screws 21.This bar is journalled by means of a bolt 23 upon a double rocker arm 24which is pivotally movable about a pivot axis 25 secured to the carrierarm 5 and to which also one end of a link 26 is secured, the other endof which is linked to rockable crank 23 (see also Fig. 3). The latter isjournalled on an axle 29 which is disposed transversely of the arm 4 andis secured against displacement by screws 30. The central position ofthe rockable crank 28 is secured by means of two set collars 31 and 32.Another arm 33 having a ball shaped end is provided on crank 28 to whicha connecting rod 34 is connected which at its other end encompasses anadjustable cam 35 provided upon the drive shaft 6. Cam element 35 isprovided with an adjusting member 36 having a detent or stopping groove37 which is engageable by a detent 38 provided on the other end of thebridge 15.

The cams 12 and 35 with their respective adjusting members 13 and 36 areof the well known type disclosed in Us. Patents 2,128,031, 2,161,579 and2,491,449, as well as in German Patent 866,444, which illustratedifferent embodiments of such adjustable cams.

The cam mechanisms employed in applicants machine operate in accordancewith the same principle, only one of them being illustrated in Figs. 6and 7. The setting or adjusting member 13 comprises a base plate 72which 'portion 43. spring 44 (Fig. 2), which restrains the detents 16and 33 is secured by means of a screw 73 to arm shaft 6. A setting disc74 rotatable relative to shaft 6 and the cam support 75 are mounted onshaft 6 adjacent to the plate 72. 'A pair of collar, screws 76extendthrough members 72, 74 and 75 and are supported against base plate72 bynuts 77 while being slidable in arcuate slots 78 provided in disc 74 andin straight slots 79 of. the cam support 75. Thus, setting disc 74 isrotatable relative to shaft 6 through an angle corresponding to thelength of slots 78, while the cam support 75 may be movedperpendicularly in slots 79 without rotary movement relative to shaft 6.V

Shifting of the cam support 75 transversely of the arm shaft 6 iseffected by relative ,movement between the'setting disc 74 and baseplate 72 in that a pin 89 secured in the cam suPPDrt 75 is guided in anarcuate slot 81 of the disc 74. A' ratchet bolt 83 which engages ratchetteeth 84 in disc 74, and is biased by spring 82 to retain disc 74,yieldingly, protects said disc '74 and thereby said cam support 175against unintentional rotation.- The shifting is effected in that thedetent 16 is caused to engage the notch orv groove 14 to hold thesetting disc 74, while shaft 6 and with it the base plate 72 and camsupport 75 are rotated against the action of the spring biased means 82,83, 84 so that the setting of the eccentricity of cam 12 is elfected byway of the pin and slot guiding means 80, '81. The extent of theeccentricity adjustment is reflected by the movements of the machineelements thereby affected, such as the needle bar 10.

A rearwardly extending arm 39 (Fig. 5) is provided on bridge '15 whichis rotatably secured by means of a collar screw 49 to a support 41 whichlatter is provided by means of screws 42 upon the flattened centerhearing The bridge 15 is biased by means of'a depends on themagnitude ofthe feeding movement, and this is achieved by the journalling of therocker crank 65 in the arms 27 of the rockable crank 28.

For operation the spring biased push button 47 is pressed against bridge15 and'lowers the same against the pressure of spring 44 until thedetents 16 and 38 contact the setting members 13 and 36. Whilemaintaining the finger pressure on button 47 the drive shaft 6 is turneduntil the detents 16 and 38 are seated in the grooves 14 and 37. Themagnitude'of the continuing rotation of the drive shaft .6 determinesthe magnitude of the change in the stitch length. Upon termination ofthe adjusting procedure the pressure on button 47 is released so thatthe button and the bridge return to their positions of rest under thepressure of the corresponding springs.

Having now described our invention with reference to the embodimentthereof illustrated in the drawings, ,we do not wish to be limitedthereto, but what we desire to protect by Letters Patent of the UnitedStates is set forth in the appended claims. a

We claim: a r

1. Looper and feed mechanism for a double chain stitch sewing machinehaving a housing including a machine arm, a main drive shaft supportedin said arm and compound feeding means comprising a needle bar, a firstreciprocable member and a needle bar oscillator supporting said needlebar for swinging movement and opcratively connected to said reciproeablemember; first adjustable cam means mounted on said drive shaft andconnected to said first reciprocable member for imparting swingingmovement to said needle bar oscillator, a feed bar, a feed dog supportedendwise of said feed ba r befrom engaging the grooves 14 and 37 of thecams 12 and 35. The spring 44 is supported on the other hand 7 upon thebearing member 43 and is secured by a pin 45.

A spring biased push button 47 provided in the cover 46 of the machinearm above and centrally of bridge 15 is operative to simultaneously setthe two cams 12 and 35. This insures that the needles 11 and thematerial feed dog 20 operate in synchronism.

' The raising and lowering movements of the material feed dog 20 are derivedby means of a cam 48 from main drive shaft 6 and are transmitted byway of a double armed lever 54 journalled centrally on a pin 51, whichis journalled in the carrier arm 5, and by way of a double link 52 tothe forward part of the material feed bar 22.

A pair of thread carrying loopers 53 which cooperate with the needles 11and move transversely of the direc tion of feed are secured to theforward end of a looper shaft 57 which is arranged in sleeve bearings54, 55 and 56 for axial and pivotal movement. A crank 58 is clamped tothe rear end of the looper'shaft 57 which is linked for operation by wayof a pull rod 59 to a crank 60 secured to the end of the drive shaft 6.In this Inwner loop catching and casting movements are imparted to theloopers 53 in a direction transversely of the direction of sewing.

A pair of claws 61 are secured to the looper shaft 57 (Figs. 2 and 3)for the needle evading motions of the loopers 53 between which a slideblock 63 is received which is journalled on a bolt 52. This bolt 62, issecured to the end of an arm 64 of an angmlar rocker crank 65 by meansof a screw 66. The rocker crank 65 is secured in the arms 27 of thecrank 28 upon an axle 67 fastened in place by screws 68 and is connectedat its other arm 6? (Fig. 2) by means of cam connecting rod 70 to a cam71 provided upon the drive shaft 6. The looper shaft 57 is thussubjected to a constant needle evading motion derived from cam 71 and amotion which low said needle bar and a looper shaft extending generallyparallel to said drive shaft and supporting a looper below said feeddog; a second reciprocablemember operatively connected to said loopershaft, a first connecting rod and a cam on said drive shaftfor'imparting constant reciprocating movement to said looper shaft; arockable member supported in said housing having one arm operativelyconnected to said feed bar and 'pivotally supporting said secondreciprocable member, second ad justable cam means mounted on said driveshaft and means including a second connecting rod having one endoperatively connected to said second adjustable cam means and anotherend operatively connected to the other arm. of said rockable member forimparting reciprocating motion to said feed bar and for superimposingreciprocating movement on said looper shaft by way of said secondreciprocable member; and rocking means on said looper shaft and onsaiddrive shaft connected to impart rocking movement to said looper shaft.

2. Looper and feed mechanism for a den le chain stitch sewing machinehaving a housing including a machine arm, a main drive shaft supportedin said arm and compound feeding means comprising a needle bar, a firstreciprocable member and a needle bar oscillator supporting said needlebar for swinging movement and operatively connected to said reciprocablemember; first adjustable cam means mounted on said drive shaft andconnected to said first reciprocable member for imparting swingingmovement to said needle bar oscillator, a feed bar, a feed dog supportedendwise of said feed bar below said needle bar and a looper shaftextending generally parallel to said drive shaft and. supporting alooper below said feed dog; a second reciprocable member openativelyconnected to said looper shaft, a first connecting rod and a cam on saiddrive shaft for imparting constant reciprocating movement to saidlooper. shaft; a rockable member supported in said housing having onearm operatively connected to said feed bar and pivotally supporting saidsecond reciprocable member, second adjustable cam means mounted on saiddrive shaft and means including a second connecting rod having one endoperatively connected to said second adjustable cam means and anotherend operatively connected to the other arm of said rockable member forimparting reciprocating motion to said feed bar and for superimposingreciprocating movement on said looper shaft by way of said secondreciprocable member; and rocking means on said looper shaft and on saiddrive shaft connected to impart rocking movement to said looper shaft,each of said first and said second adjustable cam means including a camsetting disk having a detent portion and a member in operativeengagement with a cooperating portion of the cam associated therewithadapted to move said cam relative to said shaft in response to rotationof said shaft and means adapted to engage said first and secondadjustable cam means operative to maintain the position of sid disksrelative to each other.

3. Looper and feed mechanism for a double chain stitch sewing machinehaving a housing including a machine arm, a main drive shaft supportedin said arm and compound feeding means comprising a needle bar, a firstreciprocable member and a needle bar oscillator supporting said needlebar for swinging movement and operatively connected to said reciprocablemember; first adjustable cam means mounted on said drive shaft andconnected to said first reciprocable member for imparting swingingmovement to said needle i-bar oscillator, a feed bar, a feed dogsupported endwise of said feed bar below said needle bar and a loopershaft extending generally parallel to said drive shaft and supporting alooper below said feed dog; a second reciprocable member operativelyconnected to said looper shaft, a first connecting rod and a cam on saiddrive shaft for imparting constant reciprocating movement to said loopershaft; 21 rockable member supported in said housing having one armoperatively connected to said feed bar and pivotally supporting saidsecond reciprocable member, second adjustable cam means mounted on saiddrive shaft and means including a second connecting rod having one endoperatively connected to said second adjustable cam means and anotherend operatively connected to the other arm of said rockable member forimparting reciprocating motion to said feed bar and for superimposingreciprocating movement on said looper shaft by way of said secondreciprocable member; and rocking means on said looper shaft and on saiddrive shaft connected to impart rocking movement to said looper shaft,each of said first and said second adjustable cam means including -a camsetting disk having a detent portion and a member in operativeengagement with the cam associated therewith adapted to move said camrelative to said shaft in response to rotation of said shaft and meansadapted to engage said first and second adjustable cam means operativeto maintain the position of said disks relative to each other, saidmeans comprising a yoke having a detent for each said disk adapted toengage the corresponding detent portion in the associated disk.

4. In a sewing machine having a housing supporting a drive shaft andprovided with compound feeding means comprising a needle bar, a needlebar oscillator reciprocably supporting said needle bar, a feed bar, afeed dog supported endwise of said feed bar below said needle bar and alooper shaft extending generally parallel to said drive shaft andsupporting a looper below said feed dog, reciprocable means having oneend operatively connected to said drive shaft and another end connectedto said looper shaft for imparting constant reciprocating movement tosaid looper shaft, and rockable means pivotally supported in saidhousing having one end opertively linked to said drive shaft and anotherend presenting a movable pivot connected to said feed bar adapted toimpart reciprocating motion to said feed dog, said reciprocable meansbeing pivotally supported intermediate its said one end and said otherother end on said movable pivot in a manner to snperimpose the movementsof said rockable means on said constant movement of said looper shaft.

References Cited in the file of this patent UNITED STATES PATENTS1,419,462 Maier June 13, 1922 2,282,047 Graesser May 5, 1942 FOREIGNPATENTS 474,710 Germany Apr. 11, 1929 500,869 Germany June 25, 1930866,444 Germany Feb. 9, 1953 72,915 Norway July 3, 1950

